The study will be conducted on a group of healthy individuals aged 18 - 35 years. After
an interview confirming that the subject does not have exclusion criteria and inclusion
criteria apply. Written consent to participate in the study and next anthropometric
measurements will be taken using a scale and tape measure. The subjects will be informed
in detail about the procedure and the form of the measurements, the way in which they are
to be taken, and will be familiarized with the measuring instruments and their principles
of operation. Then, in accordance with the study protocol, specific measurements will be
taken of the rectus femoris, medial vastus and lateral vastus muscles using surface EMG
of a non-invasive nature.
Study participants will undergo the following measurements:
Measurement of the MVIC (maximum voluntary isometric contraction) of the quadriceps
femoris, in a sitting position with the lower leg flexed to 90 degrees, next MVIC of
the quadriceps femoris in supine with knee fully extended (0 degrees).
Measurement of muscle activity during elevation of the straightened lower limb
(ASLR) in supine without knee brace.
Measurement of muscle activity during ASLR in supine position with knee brace. Ad.a.
Measurement of quadriceps maximum electric signal of the dominant lower limb using
surface EMG in a seated position with the trunk stabilized with hands behind the
pelvis and the lower leg flexed to 90 degrees, stabilized in the distal part
(without taking the foot) against a stationary object (belt) to execute maximal
volitional isometric quadriceps muscle contraction. Next MVIC in supine position,
with knee fully extended, pushing back of the knee into hand of an examiner without
lifting heel.
Ad.b. Measurement of quadriceps excitability using surface EMG in supine position without
orthosis. The subject raises the tested limb (dominant) by touching the anterior surface
of the tibia to a pole set at 30 cm at first sound of metronome set at 60 BMP, then hold
the leg for the next beat, and next lowers the limb at the next metronome sound. This
action is repeated three times in a row without any brake.
Ad.c. Measurement of quadriceps excitability of the dominant lower limb using surface EMG
in supine position with knee extension brace on. Measurement performed in three variants:
The subject raises the test limb (dominant) by touching the anterior surface of the
tibia to a pole set at 30 cm at first sound of metronome set at 60 BMP, then hold
the leg for the next beat, and next lowers the limb at the next metronome sound.
This action is repeated three times in a row without any brake.
The test subject is asked to apply maximum tension to the quadriceps then
maintaining the tension he/she raises the limb touching the front surface of the
tibia to the pole placed at the height of 30 cm at first sound of metronome set at
60 BMP, then hold the leg for the next beat, and next lowers the limb at the next
metronome sound. This action is repeated three times.
Before the test, the test subject is verbally instructed to 'Try, despite the
orthosis holding your knee straight, to bend the knee and raise the leg so that the
quadriceps do not tense'. Then, lift the limb touching the front surface of the
tibia to the pole placed at the height of 30 cm at first sound of metronome set at
60 BMP, then hold the leg for the next beat, and next lowers the limb at the next
metronome sound. This activity is repeated three times.
Between MVICs and test trial it was 30s brake. MVICs were hold for 3 seconds. The time
for the full test is approximately 15-20 minutes per participant. Statistical analysis
will be performed using Statistica and/or JASP software. The study will be carried out
with a minimum of 20 adults aged 18 - 35 years. The exact number of participants in the
study, will be determined after performing an a-priori sample size estimation after
collecting data from the first 10 people examined. Eligibility of subjects will include a
subject and physical examination by a physiotherapist.
Inclusion criteria: age between 18-35 years, no contraindications to physical exercise,
ability to perform the required commands without pain or discomfort, full range of motion
of the knee joint.
Exclusion criteria: those with a history of knee and/or hip surgery, damage to
ligamentous structures of the knee joint in the past treated conservatively or meniscus
treated conservatively, muscle and tendon injury of the knee joint area in the past 3
months.